Runout Date- An extra time that an employee can submit manual claims for services render in the previous plan year to be reimbursed for that previous plan year's funds.
Grace Period- If your employer offers it, this is the last date a member can create a new qualified expense and draw from the previous year's funds. Grace period acts like an extended end date, since the employee can submit new claims and swipe their debit card from the current year while paying with the previous year's funds.
Rollover(Carryover)- If any funds are left in the account at the end of the plan year. The employer might move the funds into the next plan year. The rollover funds will not affect the maximum annual election for the new year. Once funds have moved to the new plan year, only the funds can be used for services that occurred during the new plan year.
**A rollover does not count against the annual limitation, you can still contribute up to $2,750(for 2020) even if you rollover $550(for 2020) from the previous plan year.
Suppose you have an FSA account in 2020 and there's a 90-day grace period and run-out period.
Run-out period: You can use your 2020 left funds to submit any eligible expenses that happened in 2020 by 3/31/2021.
Grace period: You can use your 2020 left funds to any eligible expenses that happen from 1/1/2021 to 3/15/2021 by 3/15/2021.
Rollover: You can use part of your 2020 left funds (up to $550 for 2020) to any eligible expenses that happen from 1/1/2021 to 12/31/2021 by 12/31/2021.
Note: The key difference between the Runout Date and the Grace Period is the dates of service.